Developing chamber for developing fume sensitive printing papers



Feb. 2, 1954 R. F. MARTLIN DEVELOPING CHAMBER FOR DEVELOPING FUME SENSITIVE PRINTING PAPERS Filed March 26, 1952 I Quanta? mmm Httmr Patented Feb. 2, 1954 DEVELOPING CHAMBER FOR DEVELOPING FUME SENSITIVE PRINTING PAPERS Robert Frederick Martlin, Hamilton, Ontario, Canada, assignor to Martlin & Lawrie Limited; Hamilton, Ontario, Canada, a corporation of Ontario Application March 26, 1952. Serial N 0. 278,573

4 Claims. 1

My invention relates to improvements in developing chambers for developing fume sensitive printing papers, of the type wherein the upper face of the chamber contains perforations and over which face the sensitized paper is passed to be subjected to fumes rising from developing fluid, such as ammonia, contained within the chamber.

The invention is particularly directed to chambers used in the ammonia fume developing of diazo sensitized printing paper, as is widely used in the reproduction of engineering and architectural drawings and the like; the object of the invention being to overcome the deficiencies of the standard perforated chamber top wherein the unpierced portions of the top form a barrier against the fumes contacting the paper passing thereover.

In carrying out the invention I provide an ammonia containing chamber wherein the orifices in its upper face are in the form of louvers extending transversely and uninterruptedly across the path of travel of the printing paper thereover, whereby the sensitized surface of the paper is completely and evenly subjected to the fumes rising through the louvers.

A further and particular object of the invention is to provide a construction wherein the louver openings are formed by spaced apart substantially parallel ribs extending across the path of travel of the printing paper, the ribs having relatively narrow crown portions upon which the printing paper slides and from which crown portions faces of the ribs are inclined downwardly to constitute ammonia fume containing pockets communicating with the louver openings and bounded by the inclined faces of the ribs and the sensitized face of the paper passing thereover.

With the foregoing and other objects in view as shall appear, my invention consists of a fume developing chamber constructed and arranged all as hereinafter more particularly described and illustrated in the accompanying drawings in which:

Fig. 1 is a plan view of the fume chamber, having its central portion broken away and showing the rib and louver arrangement of its upper face.

Fig. 2 is a vertical cross-sectional view through a portion of a printing machine wherein the fume chamber is contained.

Fig. 3 is an enlarged view of a fragmentary portion of the rib arrangement as shown in Fig. 2.

Fig. 4 is a similar view to Fig. 3 illustrating an alternative form of rib construction.

Like characters of reference indicate correspending parts in the different views of the drawing.

The general arrangement of the chamber and printing paper conveying endless belt, shown in Fig. 2, follows standard practice wherein the upper perforated face of the chamber 2 is of convex form and over which passes an endless belt 3 carried upon suitably driven rollers The paper to be developed is either mechanically or manually pushed up the slide plate 5 to enter between the face of the belt 3 and the curved perforated face of the chamber 2 whereby the paper is carried by the belt across the perforated face of the chamber to be exposed to the fumes, and thereafter deposited within a suitable receiving tray 6.

In my invention I replace the usual paper receiving perforated tank face by a plurality of parallel spaced apart louver forming ribs 1 which extend across the open face of the tank transversely of the path of travel of the printing paper thereover. As will be clearly seen upon reference to Fig. 3, the ribs are of inverted channel form to provide strength with lightness, and also have their outer faces 8 inclined downwardly from the paper in the direction of its travel, whereby the paper only rests upon the narrow crown portions 9 of the ribs. By forming the ribs with inclined faces 8, they constitute fume containing pockets I0 communicating with the louver openings II and bounded by the inclined faces of the ribs and the sensitized face of the paper passing thereover.

It will thus be appreciated that at any given instant of the papers travel over the chamber face that it will be completely exposed to the developing fumes apart from the small areas of the papers surface which are at that instant resting upon the crowns of the ribs, and that in its continuous movement across the ribs, the paper is entirely and evenly exposed to the developing fumes.

Fig. 4 illustrates a slight modification of the invention wherein the crowns E2 of the ribs 13 are located intermediately of the width of the ribs wherein each rib is formed with a pair of sloping outer faces I4 which form fume containing pockets l5.

From the foregoing description it will be apparent that I provide an arrangement which overcomes the fume exposure deficiencies which are inherent in developing machines wherein the upper face of the chamber is covered by a perforated plate over which the paper slides, for although it is standard practice to stagger the perforations so that they overlap in the direction of the path of travel of the paper, there is always a relatively large proportion of the papers surface which is not being exposed to the fumes at any instant of the papers travel thereover.

By my arrangement a very large percentage of the papers surface is exposed to the fumes at any instant in its travel, and as the rib crowns are relatively narrow and rounded at their edges, there is little surface contact between the sensitized face of the paper and the ribs, :anr'l therefore no scoring of or drag upon the :paper in its passage across the ribs.

While I have shown and described a .par'ticu lar embodiment of my invention, it is to be understood that I may make any such changes and alterations as I may at any time deem necessary without departing from the spirit of my invention as set forth in the appended claims.

What I claim as my invention is:

1. In a developing machine the combination of: a developing chamber; a plurality of stationary parallel spaced-apart rib members defining a louvered face for said chamber through which gas may escape therefrom; a belt moveable over said louvered face; a narrow belt engaging crown portion on each of said rib members; and an inclined face on each of said rib members extending from th crown portion thereof to de- 4 fine in conjunction with said belt a gas containing pocket.

2. In a developing machine the combination claimed in claim 1 wherein each rib member is formed of sheet metal of generally channel-like form in crosslsection.

3. In a developing machine the combination claimed in claim 1 and means for moving said belt in a direction over the inclined face of each rib member toward the crown portion thereof 4. In a developing machine the combination claimed in claim 1 wherein each rib member is formed of sheet metal of generally channel-like form in cross :sectionand means for moving said belt in a direction over the inclined face of each rib member toward the crown portion thereof.

ROBERT FREDERICK MARTLIN.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,009,962 Kurten July 30, 1935 2,200,451 Kunstadter May 14, 1940 2,475,809 Sullivan et al July 12, 1949 FOREIGN PATENTS Number Country Date 272,288 Switzerland Mar. 16, 1951 

